Issue

• We have a RHEL 6.3 server that is crashing during the time it is performing its nightly backups.
• The following errors were observed in dmesg output while the issue is occurring:

INFO: task dsmc:1094 blocked for more than 120 seconds.
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
dsmc          D 0000000000000001     0  1094      1 0x00020000
ffff88013b12bc58 0000000000000086 ffff88013b12bbd8 ffffffff81096591
ffff88013b12bcb0 ffff88013b12bd18 00000000ffffffff 0000000000000286
ffff880138359ab8 ffff88013b12bfd8 000000000000fb88 ffff880138359ab8 Call Trace:
[<ffffffff81096591>] ? lock_hrtimer_base+0x31/0x60  [<ffffffff8109245e>] ? prepare_to_wait+0x4e/0x80  [<ffffffff81116625>] __generic_file_aio_write+0xc5/0x480
[<ffffffff81092170>] ? autoremove_wake_function+0x0/0x40  [<ffffffff81116a4f>] generic_file_aio_write+0x6f/0xe0  [<ffffffffa00a4131>] ext4_file_write+0x61/0x1e0 [ext4]  [<ffffffffa00a40d1>] ? ext4_file_write+0x1/0x1e0 [ext4]  [<ffffffff8117b39a>] do_sync_write+0xfa/0x140  [<ffffffff81092170>] ? autoremove_wake_function+0x0/0x40  [<ffffffff812136c6>] ? security_file_permission+0x16/0x20
[<ffffffff8117b698>] vfs_write+0xb8/0x1a0  [<ffffffff8117c0b1>] sys_write+0x51/0x90  [<ffffffff810bcbb5>] ? compat_sys_time+0x25/0x60  [<ffffffff8104a890>] sysenter_dispatch+0x7/0x2e